GENEVA (Reuters) -Indirect carbon emissions from the operations of four of the leading AI-focused tech companies, Amazon ( AMZN ), Microsoft ( MSFT ), Alphabet and Meta, rose on average by 150% from 2020-2023, as they had to use more power for energy-demanding data centres, a United Nations report said on Thursday.

The use of artificial intelligence is driving up global indirect emissions because of the vast amounts of energy required to power data centres, the report by the International Telecommunication Union (ITU), the U.N. agency for digital technologies, said.

Indirect emissions include those generated by purchased electricity, steam, heating and cooling consumed by a company.

Amazon's ( AMZN ) operational carbon emissions grew the most at 182% in 2023 compared to three years before, followed by Microsoft ( MSFT ) at 155%, Meta at 145% and Alphabet at 138%, according to the report.

The ITU tracked the greenhouse gas emissions of 200 leading digital companies between 2020 and 2023.

Meta, which owns Facebook and WhatsApp, pointed Reuters to its sustainability report that said it is working to reduce emissions, energy and water used to power its data centres.

The other companies did not respond immediately to requests for comment.

As investment in AI increases, carbon emissions from the top-emitting AI systems are predicted to reach up to 102.6 million tons of carbon dioxide equivalent (tCO2) per year, the report stated.

The data centres that are needed for AI development could also put pressure on existing energy infrastructure.

"The rapid growth of artificial intelligence is driving a sharp rise in global electricity demand, with electricity use by data centres increasing four times faster than the overall rise in electricity consumption," the report found.

It also highlighted that although a growing number of digital companies had set emissions targets, those ambitions had not yet fully translated into actual reductions of emissions.